Design and Construction of a Standard Planetary Microfilming Camera Target Array (PMTA)

Rochester Institute of Technology

RIT Scholar Works

Theses

Thesis/Dissertation Collections

1972

Design and Construction of a Standard Planetary

Microfilming Camera Target Array (PMTA)

Bruno Glavich

Richard Johnson

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Recommended Citation

Design and Construction of a Standard

Planetary Microfilming

Camera Target

Array

(PMTA)

by

Bruno B. Glavich and

Richard T. Johnson

An Abstract

A thesis submitted in partial fulfillment of the require ments for the degree of Bachelor of Science in the School of Photographic Sciences in the College of Graphic Arts and

Photography

of the Rochester Institute of

Technology

June,

1972

ABSTRACT

After _researching the current applications, problems, and evaluation

techniques of _{planetary microfilming systems,} the authors designed and

constructed a standard

Planetary Microfilming

camera Target

Array (PMTA)

that _essentially satisfied three _criteria, i.e. 1) inexpensive _{to produce,}

2)

simple to _use, and

3)

satisfies _testing criteria for both _microfilming

equipment manufacture and user. Ten evaluation parameters were incor

porated in two targets PMTA-I and PMTA-II. PMTA-I includes tests for

1) resolution,

2)

readability of printed _matter,

3)

reduction _ratio,

4)

exposure and _processing,

5)

full field visual

distortion,

and

finally

6)

corner visual distortion. PMTA-II was designed to _evaluate,

7)

quan

titative

distortion,

8)

continous

tone,

9)

evenness of

illumination,

and

ACKNOWLEDGEMENTS

The authors would like to thank the people of Photographic Sciences Cor

poration for their technical assistance and moral support.

TABLE OF CONTENTS

Page

List of Figures v

List of Tables vi

Chapter I An Introduction 1

Footnotes for Chapter I 6

Chapter II Design 7

1) Resolution 9

2)

Readability

of Printed Matter 14

3)

Reduction Ratio 15

4)

Exposure and Processing 17

5)

Full Field Distortion 17

6)

Corner Distortion 18

7)

Quantitative Distortion 19

8)

Continous Tone 20

9)

Evenness of Illumination 20

10) Alignment of

Imaging

System 20

Footnotes for Chapter II 22

Chapter III Construction 24

Appendix A

Currently

Utilized Resolution Targets - Applications - Speci

fications

Appendix B Instructions for the Use of the NBS

Microcopy

Resolution

Test Chart

Appendix C Instructions for the Use of PMTA

List of References

List of Figures

Figure Number Page

1. Schematic Diagram of Typical

Planetary

and

Rotary

Systems 3

2. 2.5x Reduction of Background Format of PMTA-1

Showing

ll

a) Center Resolution

Box,

b) Tangentially

Located Corner

Resolution

Boxes,

c) Border 11" x 14" and 8-J" x 11" For

mats, and

d)

Reduction Ratio Line Segments

3. Corner Grid Section Used in the Evaluation of Distrotion 13

4. 2.5x Reduction of Background of PMTA-II 26

5. 25x Magnification of Resolution Groups

8.0,

9.0 and 10 27

6. 2.5x Magnification of Final Resolution Target 28

7. Type Style Box 29

8. Reduction Ratio Line Segments 29

9. Compos it PMTA-I 30

List of Tables

Page

I Maximum and Minimum Values of Possible Resolution after 12

Target Has Undergone Various Specified Reductions

II Maximum and Minimum Values of Possible Resolution after 12

Target Has Undergone Various Specified Reductions

III Minimum Resolutions

Necessary

for Compliance with Mil 13

spec. 9868 D

IV Comparable Resolution for Line Widths at Various Speci- 18

fied Reductions

CHAPTER I

Introduction

Although the concept of _{microphotography has} been in existence _nearly

as

long

as the use of photography

itself,

microfilming as a _widely

used tool for information storage has a _relatively recent history.

Several types of microcameras are _presently in use today. The _rotary

microfilm camera employs a dynamic system in which both the object and

image plane are in motion

during

the period of exposure. The planetary

microfilming camera _normally employs a camera head which is mounted on a

vertical column centered over and perpendicular to horizontal plane sur

face.

During

exposure both the film and the object to be photographed

remain motionless. Figure 1 demonstrates graphically the operation of the

planetary and rotary systems. A third microcamera system utilizes a _step

and repeat system in which the object to be photographed is placed on a

copyboard and the back of the camera has the capability of adjusting its

horizontal and vertical axis to allow several exposures with exact po

sitioning on the image plane at the film surface.

Each camera system has its advantages over the other system but the

Itna.j<Z

P/an<

Lights

Object

P/ane

3>

Ocomcnl

Fee.

J

roll

Liqhi:

7

x:

Sli+

Lens

i

Spool

3U:

Rl

m

FIGURE 1

The planetary systems are used _primarily because of their relatively low

expense and great

flexibility

in use. The cameras are of two basic

sizes, large and small. The break off point for this classification is

determined

by

the size of format to be photographed. The 36 inch

by

24

2

inch format is the break off point most _commonly used. That is to _say,

that formats larger than this specified size

belong

to the larger camera

system while smaller formats are primarily photographed

by

the small

camera.

In our _study we have concerned ourselves with the smaller format cameras

which are _primarily used to record legal

documents,

small engineering

drawings,

and other such small format material. These smaller cameras are

of two basic types. One has a fixed focus and fixed reduction and a

second has both variable reduction and focus.

If a good method of planetary microfilming system evaluation was to be

developed,

it must fulfill several requirements.

It must not only yield an adequate indication of what the

system is

doing

while _{operating correctly,} but more important the evalua

tion method must give an immediate indication of a fault in this

photo-optical system. _{As yet,} much of the microfilming system evalua

tion has been used on the go-no go method. That is to _say, if the micro

filmed results were _useable, then the system was said to _{be working,}

and if not useable -

try

_again. The _useability of the product

necessarily

proposed herein will be based on such go - _{no go method.}

However,

finer

and more quantitative evaluation parameters will be employed to achieve

this end.

As indicated

by

the title of this _paper, there were two distinct phases

of _study - design

.and construction of a standard

Planetary Microfilming

camera Target

Array (PMTA).

The design phase _{included: 1)} an indepth _study

of microfilming's present _{uses, needs,} and _standards,

2)

a determination

and justification of the evaluation parameters to be included in the

PMTA,

and

finally 3)

the layout specifications for the production of the target.

The construction phase included the photo-mechanical generation of individual

members of the _array and subsequent gatherings of these members into two

FOOTNOTES FOR CHAPTER I

1.)

Mees,

C.E.,and T. H.

James,

"The

Theory

of the Photographic

Process",

Third

Edition,

Macmillan,

New

York, 1967,

p.542.

2.)

Bujkovsky, G.,

and James L.

Martin,

"The

Planetary

Camera",

Micro

CHAPTER II

DESIGN

When originally considering the design of a composit planetary test tar

get, it was thought that a target could be made of one universal format

which would take into consideration all possible microfilm camera formats

and uses. As our research progressed it was found necessary to continually

reduce the scope of our thesis. The final result of our efforts for a

composit standard

Planetary Microfilming

camera Target

Array (PMTA)

in

cluded two targets

(PMTA-I

and PMTA-II) which contained a total of ten

evaluation parameters. These targets were designed _only for format sizes

of &" x 11" and 11" x

14",

and format reduction ratios of

16x,

24x,

28x

and 3Ox.

PMTA-I includes tests for 1)

Resolution,

2) Readability

of printed _matter,

3)

Reduction ratio,

4)

Exposure and _processing,

5)

Full field

distortion,

and

6)

Corner distortion. PMTA-II was designed to evaluate

7)

Quantative

distortion,

8)

Continous

tone,

9)

Evenness of illumination and 10) Align

ment of

imaging

system.

The

following

arguments will consider the design of each individual evalua

tion parameter of PMTA-I and

PMTA-II,

in the numerical _sequence, presented

PMTA-I

1) Several important parameters affect the quality of a microfilm image. Be

cause of the nature of _{microphotography,} one of the more important areas

concerns the _ability of the photo-optical system to image small objects

with good definition. This concept leads to the idea of:

Resolution;

the

ability to render visible fine detail of an _object, and

Resolving Power;

the degree to which a

lens,

optical _system, or image material is able to

2

define the detail of an image. Various _resolving power measurement

3

methods have been developed as predictors of the resolution capabilities

of a photo-optical system. None of these _methods,

however,

proports to

indicate _exactly what can be resolved and what cannot. Taubes _states, in

his paper on

legibility

of microfilm

images,

that "images at different

reduction ratios resolving the same resolution symbols will not permit

4

the _reading of the same letter height".

Therefore,

many methods of RP

measurement yield only an indication of the system's capabilities.

The National Microfilm Association

(NMA)

recognizes the NBS

Microcopy

Re

solution Chart as the method to be utilized when _attempting to determine

5

the resolving power of a microfilmed image. Therefore in an attempt to

existing standards, the

Microcopy

Resolution Test Chart was utilized as

the _primary means of resolution measurement. The composit _array incor

porates 9 resolution targets. The first target was placed on axis in the

center of the _array as shown in figure 2. This target has groups of elements

of five lines each with frequencies of spacing varying from 1.0 lines/mm to

18 lines/mm. Table 1 shows the maximum and minimum values of possible re

solution after the target has undergone various specified reductions.

Microfilm systems _normally operate with a resolution of approximately

100 lines per milimeter.

Therefore,

even after blow back and/or

duplicating

of microfilmed material and subsequent loss of resolution, the resolution

target would be capable of _yeilding a resolution measurement.

As shown in figure 2 there are also four sets of, two _each, resolution

targets mounted _tangentially

80%

of the diagonal distance to their 8%" x 11"

and 11" x 14"

formats,

respectively. These targets are also NBS

Microcopy

Resolution Test Charts but

they

_only contain

frequency

groups 2.0 lines/mm

through 10 lines/mm.

Availability

of space and resolution capabilities

dictated the use of this range of resolution groups. Table II indicates

the possibile maximum and minimum resolution for this target at various

specified microfilm reductions. Often military creteria must be met to

satisfy specifications. Table II yields the lowest resolution group number

which must be resolved in order to meet with _military line width and print

c) Boarder sections

h:tttte^

b)

Corner "Res. Boxes

a) Center Res.

Boxes j

d)

Reduction ratio line segments

Figure 2

2.5x Reduction of Background Format of PMTA-I

Showing

a) Center Resolu

tion,

b)

Tangentially Located Corner Resolution

Boxes,

c) Border of

11"

TABLE I

Maximum and Minimum Values of Possible Resolution after Target Has Undergone Various Specified Reductions

Reduction Minimum Resolution Maximum Resolution

Group

1.0

Group

18

16x 16 1/mm 288 1/mm

24x 24 1/mm 432 1/mm

28x 28 1/mm 504 1/mm

30x 30 1/mm 540 1/mm

i.e. lines per millimeter

TABLE II

Maximum and Minimum Values of Possible Resolution after Target Has Undergone Various Specified Reductions

Reduction Minimum Resolution Maximum Resolution

Group

2.0

Group

10

16x 32 1/mm 160 1/mm

24x 48 1/mm 240 1/mm

28x 56 1/mm 280 1/mm

1 "3

TABLE 3

Minimum

resolutions _{necessary for compliance}

with M. L. spec. 9868D

Reduction

Ratio 16x 24x 28x 30x Smallest NBS Pattern read 7.1 5.0 4.5 4.5 Resolution lines/mm 114 120 126 135 11

14"f -;-T"!-' " ..,.. r

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FIG. 3

2)

Readability

of Printed Matter -

Considering

that the majority _{of matter}

contained on the format size for which this target is designed is printed

matter, a representative target could

hardly

be designed that did not

contain _varying styles and sizes of type.

g

In discussions with Alexander

Lawson,

a specialist in _typography it was

pointed out that there are

basically

two schools of type face styles used

9

most often. Almost

90%

of the general printed matter _today is printed

on one of a multitude of Roman type style. A Roman type face style is

characterized

by

its complex style and curvatures plus serifs at letter

endings. This type style is popular because of its pleasing appearance

and because of the _variety of patterns each letter

has,

thus

being

less

monotonous to read.

According

to the studies made

by Lawson,

there are

a number of _very popular Roman type face styles of which Baskerville is

one. Baskerville type style will be included in the PMTA because of its

popularity as a Roman type style.

A second type style that could not be ignored is sans serif which is

characterized

by

letters that have no serifs. The American National

Standards Institute

(ANSI)

is _{presently attempting} to standardize a type

style that is to be used in engineering drawings that are to be

micro-11

filmed. This particular sans serif type style has been developed

by

the

15

a type style that is _{clear, easily legible} and that microfilms well with

little chance of _readability error. _{Microfont is specifically known in}

the printing

industry

as a sans serif gothicstyle type with clean smooth

lines.

The target will contain a type style box with sans serif and Roman

(serif)

styles represented

by

Microfont and Baskerville respectively. Each type

style ranges in size from 4 point

(i.e.

approx. .04") to 14 point (i.e.

approx. .14") in steps of 2 points. Each point size _group is made _up of

12

4 groups of 5 _randomly chosen alphaneumeric characters. In the case of

Microfont there are no lower case

letters,

therefore all letters are of

similar height. In the case of

Baskerville,

five letter groups were

chosen to represent a _word, the first letter of which is a capital letter

and the

following

four letters of which are lower case letters.

3)

Reduction ratio is a third image quality parameter to be dealt with. The

reduction ratio is controlled

by

the optical and mechanical portions of

the photooptical system. The reduction is important to the image quality

because of the tight specifications of image blow-back. The microfilmed

image must maintain its correct reduction ratio to the object

being

photo

graphed. If the total image is too large or too _small, it is possible

16

Military

specification 9868D dictates that the reduction ratio must be

within +

0.4%

of the specified reduction ratio. The reduction ratio of

a system is often measured

by including

a line of known length on the

test object and after

being

reduced onto

film,

the image is measured with

an optical reticle and the reduction ratio is calculated by:

n j .*. _t>

j. Object line length Reduction Ratio = =-=*

=5 ?

Image line lengtn

This reduction ratio is then compared with the specified reduction ratio

to determine if it falls within specifications.

A simple and accurate method to check reduction is a criteria that is

wanted

by

the user as well as the manufacturer of _{planetary microfilming}

systems. Therefore we have to include this into the PMTA in such a way

as to construct distances in such lengths to yield a constant value at

various popular reductions.

Thus,

there would be a specific reduction

that would yield a constant value after it is reduced. This constant

value would be the same for all the reductions.

The

NMA,

in cooperation with

ANSI,

is

trying

to standardize the sizes of

documents and drawings in a similar fashion as has ISO done in order to

begin to limit and standardize the reduction ratios

basically

to 24x and

17

Therefore,

a measurement system as shown in figure 2d would be easily

measured with a magnification

loop

and retical.

4)

Exposure and _processing is also a most important parameter of considera

tion. One method for evaluation of this parameter is the introduction of

gray patches of

differing

reflectancies. After

development,

the gray

patches are then measured

by

use of a diffuse densitometer such as the

MacBeth model TD-102 transmission densitometer.

Military

Standard 9868D

requires that when a _gray patch of

50%

reflectance is imaged and

micropho-tographed,

it must have a

density

of 1.1 + 0.1. The

NMA,

in addition to

this

50%

reflectance _patch, introduced a

6%

reflectance _patch, their pro

posed

industry

standard target for large engineering drawing. In addi

tion to these _{two patches,} we have inserted a third patch of

80%

reflec

tance for a dual _{purpose, 1)} to simulate and allow the measurement of the

background

density

of a common brand of white bond paper and

2)

to yield

a three point approximation of a

Density

vs.

log

Exposure _{(Hand D)} curve.

If a microfilm user were to test his system _{periodically,} these three

points would be useful in

detecting

a change in his exposure and/or

processing.

5)

Full field distortion is the fifth area of consideration to be incorporated

in the PMTA. Image distortion is manifested

by

a

bowing

of straight line

18

optical aberration _and, in the case of microfilming, can cause engineering

drawings to be out of proportion and/or print characters to be formed

outside their matrix positions. The border outlines of the 11"

x 14"

and 8-g-" x 11" formats lend themselves to the evaluation of this para

meter. The target evaluator would subjectively determine whether or not

the border line sections displayed

bowing

appearances.

6)

Corner field distortion is the last evaluation parameter to be included

in PMTA-I. Grid sections have been placed in the four corners of the

PMTA to allow the target evaluator to _subjectively determine if there is

a noticeable amount of this off axis aberration. This grid section is

made _up of 0.1" squares. The format border lines _{passing through} the

grid section are .015". The major

1"

and "

division lines are

and the smallest interior lines are .005". These _varying line widths

can also aid the target evaluator in

judging

what line width will be

lost after subsequent microfilm copies or blow backs. Table IV indi

cates comparable resolution that the line widths represent at _varying

reductions.

TABLE IV

Comparable Resolution for Line Widths at Various Specified Reductions

Reduction

Ratio .015

Line Resolution *

.010 .005

16x 21 1/mm 31 1/mm 63 1/mm

24x 31 1/mm 47 1/mm 94 1/mm

28x

'

Reduction Line Resolution *

Ratio .015 .010 .005

30x 39 1/mm 59 1/mm 117 1/mm

* _Resolution

measures in lines/mm

PMTA-II

7)

Quantative distortion - the idea _of

mathmatically placing a numerical value

on distortion became evident when we realized that what one person would

consider too much

distortion,

another would not. This was accomplished

by defining

distortion as

_,. . . , Corner length B

Distortion =? _-7; = ,,

- =

Center length A

The target evaluator could measure distance A and distance B with a

loop

and retical and determine the quantitative distortion

by dividing

B

by

A. If there was no distortion then B/A = _{1.0. On the other}

hand,

if

we had a value for distortion greater than

1.0,

then this would be a

pin cushion distortion. If the value was less than

1.0,

then this would

be barrel distortion. The idea is that the manufacturer would have an

actual value that he could place on the amount distortion over a speci

fic area and in that _way could stand behind his product. Figure 4 illustrates

20

8)

Much of the _microfilming

being

done _today includes pictorial images of

a continous tone nature. Therefore it was deciced to include a _gray scale

of _varying reflectances. The exposure and _processing evaluation para

meter of PMTA-I already includes reflectance patches of

6%,

50%,

and

80%

PMTA-II includes four patches of

10%,

30%,

50%

and

70%

reflectances with

an overall background reflectance of80%. Even after a 30x reduction of

PMTA-II onto

film,

the 2.3mm _gray patches would _easily be measureable

with a 1mm aperture of a transmission densitometer such as the MacBeth

TD-102. These _gray patches could then be plotted on a diffuse

density

versus

log

exposure curve to attain a

day

to

day

record of the tonal

qualities of the microfilm system.

9)

Evenness of

illumination,

according to several people the authors conferred

with, could be one of the most important considerations. If the illumina

tion of the object

being

photographied is not _correct, hot spots can form

on the

image,

washing out any printed matter. It is possible to subjectively

evaluate this parameter with the use of PMTA-II

by

comparing different

sections of the background to each other. The target evaluator could

also take

density

readings of the different background sections and

allow himself a much more quantitative method of comparison.

10) Alignment of the.

imaging

system is the last parameter designed to be

by

placing PMTA-II on the object plane platform of the planetary camera

in the position _normally used for the specific format size in question.

After exposure and _processing, the distance from the 11"

x 14" or 8^-" x 11"

format border to the edge of the film is measured with a magnification

loop

and retical. If there is _any skew of the image position to the

22

'-O-F

Distance B

<>

-<p-

-i>-7

Distance A

776

7

-$

7

?

Figure 4

AO

FOOTNOTES FOR CHAPTER II

1.

)

NMA, "Glossary

of Terms for

Microphotography

and Reproduction Made

from Microimages,"

Maryland,

1964.

2.

)

Ibid.

3.

)

Appendix A displays several currently used targets and their appli

cation and specifications.

4.)

Taubes,

Earnest

P.,

"Determining

Limites of Legibilityof Microfilm

Images,"

Photo Devices

Inc.,

Rochester,

New York.

5.)

NMA,

"Inspection and

Quality

Control Standard - First Generation

(Original)

Silver Halide Microfilm,"

4th

Draft, May 1971,

p.6.

6.

)

"Micromation Film Manual,"

Stromberg

DatagraphiX

Incorporated,

San

Diego,

Calif.

July

1970,

p. 2-7.

7.)

80%

is the percentage stipulated

by

the NMA's Inspection and

Quality

Control Standard for first generation silver halide microfilm.

8.)

Alexander Lawson - Professor in the School _of

Printing

_at Rochester

Institute of Technology. Specializes in

typography,

its

history

and development. Lawson has written numerous articles for

Printing

Impressions on type styles.

9.)

This statistic has been compiled for the last 40 or so years

by

the American Institute of

Printing

in the so called

"Fifty

Books

of the Year" where the 50 best books of the year are analyzed for

24

10.)

The most popular styles of print as analyzed

by Lawson,

among

others, are

Baskerville,

Times

Roman,

Caledonia,

Garamond, Janson,

Bodoni,

and Caslon.

11.) ANSI Standard

Drafting Practices,

ANSI

Y14.2,

"Line Conventions

and _{Lettering*. Draft March}

1971,

_Proposed

Revision,

_p.18.

25

CHAPTER III

26

CONSTRUCTION

Although both the authors had had prior experience in the production of

targets and _reticals, the complex nature of the PMTA'

s construction af

forded both of us much additional thoughtful experience.

It had been thought that we could utilize a _copy of the National Microfilm

Association's endorsed

Microcopy

Resolution Test Target

but,

much to the

authors'

chagrin, copies that we attained were not of a high enough quality

to allow faithful reproduction.

Therefore,

there was no other recourse

but to produce our own five bar targets. This formidable task was

started

by

attaining artwork specifications from the NMA. Because of the

highly

reliable 5x reduction capabilities of a 12 inch lens used at Photo

graphic Sciences

Corporation,

it was decided to produce the initial art

work 25x the final size. Each of the 26 individual elements of the test

target, i.e. groups 1.0 through

18,

were produced on a precision _{x,y plotting}

table. After each element was reduced

5x,

the total target was aligned

in their correct respective positions and the complete target underwent

the last 5x reduction. Through exposure and _{processing controls,} it was

possible to contain all elements to within +

5%

of a one to one bar to

space ratio and specified size. Figure 5 shows groups

8,

9,

and 10 at

the initial 25x size. Figure 6 shows a 2.5x magnification of the target's

27

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Figure 6

31

The type style box was part of the major background artwork as shown in

the 2.8x reduction of figure 2. It was _{necessary to randomly} select the

letter as suggested in the design section and then mount each letter in

dividually

on clear mylar. After numerous groups of five

letters,

each

was mounted. The random

lettering

of each type style underwent various

specific reductions to produce the different point sizes needed. Figure

7 shows the composit type style box calling out the different point

sizes and type styles.

Lettering

was stripped onto the reduction line segments to indicate which

line segment was to be used for specific _reduction, i.e.

16x,

24x,

28x,

and 30x as seen in figure 8.

econd generation master negatives were made from the background art

work of figure 2 and the assembled targets and lettering. One third

generation master positive was produced

by

a dual contact print exposure

of the two master negatives in register. One fourth generation composit

master negative was produced

by

contact _printing the composit third

generation master positive. At this point Kodak 96D Wratten neutral

density

filters were introduced to the transparent patch sections of

the negative to allow the correct reflectances on the Positive Print Film.

It was found that the base plus

fog

level of the reflection film material

X27>

was approximately/frjL reflectance.

29

J.iioAiuhdOi7hy Cn7e B5IP I CJTWON!*lrter.CUZUCOIZC68

itiiix Woi'dii. C6Jfm Zm79a O iZC6805M7PP.N6SS OIKOG

Tlwha ah^oz bunYr Dm525

8

XM830 HWEKH XYAHQ SIDDS

KP7Yc Rho9t Umkh<I Eeafd

10

VILNU MZBSF XM330

HWEXhN

CGJfm

Zm79a

3s431

iskrY

I26FRKM

E37AU FUDWM

5C0NF

t)z7h9B5elPWo8nk8tizx!4C985

BiSAJ Z7QYI G^D7

POINT

SERI?

(BASKERVILLE)

SIZE

SANS

SERIFCMICRCFCX'.T

Figure 7

Type Style Box

SHOULD MEASURE

2F>U

AT

REDUCTION

o

!6X

2M-X

- v' ; or- >'

Figure 8

/EmAiFr.

Figure 9

7

-<-

-$-50%

V

PLANETARY

MICROFILMING

TARGET

ARRAY

(PMTA-II)

cr -tr

FIGURE 10

33

Notice that the

6%

and

50%

patches are opaque to allow a transparent mode

when in the composit negative stage.

PMTA-II was completed in the same dual registered contact print of the

second generation master line work negative and master

lettering

negative

as _{done in PMTA-I.} A subsequent composit fourth generation master nega

tive was made from the composit third generation master positive and neu

tral

density

filters were inserted at this point to allow the correct

reflectances of

10%,

30%, 50%, 70%,

and /0%.

Figure 10 shows a 2.5x

reduction of the third generation master positive.

Summary

The authors feel that _they have achieved the trl-fold purpose of their

initial objective. A PMTA has been produced that is

1)

inexpensive to

produse,

2)

simple to _use, and

3)

satisfies

testing

criteria for the user

34

APPENDIX A

CURRENTLY UTILIZED RESOLUTION

NBS MICROCOPY TEST CHART 35

LO

=

Iiil!.!

_Iii

!

125

j2,3 ;4i2.5

P50 "JJ*

7:

m

1.4

12.2 EP

12.0

1.8

1.6

DATA

Bar length-to-width ratio 24:1

Bar width-to-space width ratio 1:1

Pattern

frequency

progression

^Q/lO"

Pattern

frequency

range i to ISlp/m:

APPLICATION

For resolving power evaluation of _recording

materials and optics employed in reduction

imaging

such as microfilmi systems. For

visual _assessment; target layout does not lend

itself to photoelectronic _scanning easily.

ALPHANUMERIC BLOCK CHARACTERS

J.1E53

i 2aaa

| 3235 /.

, 4SB3

5E2S ,\a'..

;l 1E53

n 23sa

'I; 3HS5 /

; 4SB3 5E3B

Oaati yeas gess yeas i 1E53 .4

1E53

2B53 Jl 23S3 f, i

32G5

4 533

4^

5 E23 tiasT bSBS Vsbs

32^;

4 533 _ilVng 5EHQ y^sli

6aas veas

DATA

'

Bar length-to-width ratio 5:1

Bar width-to-space width ratio.... 1:1 i Pattern

frequency

progression and range

depend on the degree of the reduction of characters.

APPLICATION

Testing

resolution of

imaging

materials and

i optical systems

by by

conventional bar type

resolution patterns for evaluation

by

visual means. _{Not very} suitable for photoelectronic

36 ISO MIRE c

V

7 H -iyi / '

Ji' -4- 1

o loea _Sf eo <?S IO u a 06 t> SU ' OW 091 001 08 9 OS O 0 oooo &

OOOO OOOO oooo oooo

wooo o oooo oooo

90* e* 00

OOOO oeoo oeoo oooo

c c c c c c c

7 7 7 7 7 7 7

OS oooo oooo OOO OOOO OOO

@o

CD

DATA

Equivalent resolving power R = _7/2C

Pattern

frequency

progression

VT"

Pattern

frequency

range 2.19 to 7.79 lp/mm

APPLICATION

Primarely

used in resolving power and typographical character

legibility

for microimaging exposure and blowback _systems, and

document _copying applications. Taget'does not lend itself to

photoelectronic _scanning of the patterns.

USAF 1951

-2

IIP

MB

^S||l

o ,

335

=3

4

5

IS

jliri

1=111 ,,,0

ri p !!E4 11=5 ill =6 r2 DATA

Bar length-to-width ratio 5:1

Bar width-to-space width ratio... 1:1

Pattern

frequency

progression.. . .

Y2~

Pattern

frequency

range 25 to

900 lp/mm

APPLICATIONS

Can be used for resolving power in

'imaging

systems and optical systems.

ANNALUS

37

*''77\.a:67p::67^

Ap^yE^A-^E^OL.

6677

&:

'";

. . 4.-4;.;-4. .;, _./~V

4CV'

-F,r

'..V-:

^

^v

4 ^,

yTJA^i

7 DATA

Central to outer _ring diameter... 1:3

4 Pattern

frequency

progression. . . .

D-/2~

;; Design contrast -generally low.... 1.6:1

I

APPLICATION

V

'|

In _testing resolution performance of

}, lenses for aerial photography where low

|

contrast detail is often encountered.

7. This target is favored in Canada.

WEDGE-SHAPED RESOLUTION ELEMENTS

DATA

W707i

pmmm

Bar width and space width.. .

Resolving

power from center.

5U R.P. =

90/

r where r=distance in mm =angular separation of bars APPLICATION

Idealy

suited for detection of lens

astigmatism and other aberrations.

Not well suited for photoelectronic _scanning

38

APPENDIX B

INSTRUCTION FOR THE USE OF THE NATIONAL BUREAU OF STANDARDS

39

INSTRUCTIONS _{FOR THE USE OF THE NATIONAL BUREAU} OF STANDARDS MICROCOPY

RESOLUTION TEST CHART

The useful reduction ratio of a microcopying camera is limited

by

the

nature of the material to be _copies, the _resolving power of the

lens,

the _resolving power of the photographic material,

inaccuracy

of

focusing,

vibration, and systematic relative motion of the optical image with re

spect to the photographic material. The resolution test chart is issued

to assist _{in standardizing} the evaluation of the performance of

micro-copying systems. The test patterns are made _up of black lines on a white

background,

the lines

being

24 times _{their width,} and the lines and spaces

being

of equal width. The patterns range in spatial

frequency

from 1 to

10 lines per millimeter. Each pattern is made _up of two groups of 5

parallel

lines,

the lines in the two groups

being

oriented perpendicular

to one another. The number associates with each pattern is the number

of lines per millimeter on that pattern.

To measure the resolving power of the microcopying system, place one

chart in the center of the camera

field,

one at the center of a

long

side, and another at a corner. Orient the last two so that one _group

of lines is directed toward the center of the field. Photograph the

charts in the same manner as documents and examine the processed films

40

of lines per millimeter to be observed. For example, to view 100 lines

per _millimeter, the magnification should be between 30 and 100.

If the camera is _slightly out of

focus,

the _copy of the chart _may have

other than 5 lines in some groups. This is "spurious resolution"

and

is sometimes accompanied

by

failure to resolve at one spatial

frequency

when apparent resolution occurs at a higher frequency. If there is no

evidence of spurious _resolution, find the smallest pattern in which the

lines can be counted with certainty. The number on that pattern multi

plied

by

the reduction ratio is the measures resolving power of the system

in lines per millimeter. For _example, if the finest resolved pattern is

marked "4.0" and the reduction ratio is

29,

the resolving power is 116

lines per millimeter.

Away

from the center of the

field,

the resolution of lines directed to

ward the center is often not equal to the resolution at right angles to

that direction because of lens aberrations. If the patterns perpendicular

to one another are not equally resolved at the center of the

field,

one

should suspect camera vibration or other image motion with respect to

the film.

The resolution required to _copy type depends upon the size of

type,

the

reduction ratio, and the _quality of reproduction required. For most prac

tical purposes;

R,

the resolving power ih lines per _{millimeter; e,} the

height in millimeters of the lower case"e"

41

the reduction _ratio; and _q, an _arbitrary

"quality

index," are related

by

the

following

equation:

r

--as-e

For excellent _copy, in which the details of type are _clearly

defined,

_q

must be 8 or more. If _q is assigned a value of

5,

the _{copy may} be read

without

difficulty

although serifs and fine details of type are not clear.

If _q is

3,

_{the copy may} be read with

difficulty,

the letters _{e, c,} and o

being

partly closed.

In

1963,

the resolution chart was slightly modified. Space was left in

the center so that a 10 times reduction of the chart could be placed there

by

anyone

desiring

to extend the spatial

frequency

to 100 lines per

millimeter. The patterns from 2 to 10 lines per millimeter are in an

array that may be used as an abridged chart. Although the form of the

patterns is unchanged, the dimensions of the new charts conform more

accurately to the nominal values.

Reference: Bernard H.

Fouquet,

"The NBS

Microcopy

Resolution Test

Chart",

42

APPENDIX C

43

USE OF PMTA

PMTA-1

1)

Resolution - is _the

ability of a photo-optical system to render visible

fine detail of an object expressed as _"resolving power"

and measured in lines

/mm.

2)

Readability

of Printed Matter - Use type style representative of style

of

lettering

to be microfilmed. With a suitable magni

fication

instrument,

read the smallest _twenty letters

possible noting each one on a piece of paper. Compare

the recorded values with the actual values and noting the

number of correctly read letters. Decide how confident

you want to be that you are _{reading those} letters by:

Out of 20

%

Read

Correctly

Confidence

17 99

16

"

95

15 90

Example: If one wants to be

95%

confident of what one is _reading, then one

44

3)

Reduction Ratio - is the _{ratio of} the linear measurement of a document

to the linear measurement of the image of the same document

expressed as

16:1,

24:1,

etc. The measurement should be made

with precise enough instruments to yield.resultsmeeting your

specifications.

4)

Exposure &

Processing

- in _order to comply with accepted standards for

checking resolution, the

50%

reflectance patch should read

1.1 + .1

density

after _processing on a calibrated diffused

densitometer (such as a MacBeth TD-102)

5)

Full field distortion can _{be subjectively} evaluated

by

_examining the re

duced image of the border regions of the PMTA for possible

bowing.

i

6)

Corner distortion can be evaluated

by

the use of the corner gaid sec

tions of the PMTA.

Again,

if upon examination of the film the

corner grid section of the PMTA have a two _{fold purpose,}

1)

Corner distortion can be evaluated

by

_{examining the} reduced

image of the grid sections for possible

bowing

of lines or

a symetrical appearance of the individual _squares,

2)

The

PMTA format border

lines,

the major division

lines of the grid and the minor division lines of the

45

straight lines. The table below yields compariable resolu

tions of the three line widths at the specified reductions.

Comparable Resolutions for Line Widths a Specified Reductions

Line Widths

.015 .010 .00

Luction Line Resolutions *

16x 21 31 63

24x 31 47 94

28x 37 55 110

30x 39 59 117

* _{line resolutions are measured in lines/mm}

7)

Quantitative distortion can be measured

by dividing

the corner dis

tance

(B)

between registration marks

by

the center distance

46

8)

Continous Tone - is the

varying gradation of _gray densities between

blacks and white. For the microreproduction of continuous

tone materials the user should first determine the optimal exposure and processing adjustments for a typical pictorial

scene. When an image has been judged accepted the PMTA should

be exposed and processed under the same conditions and the

developed densities of the reflection patches should be re

corded to be used as standard reference densities for sub sequent micro-reproductions of continous tone materials.

9)

Evenness of Illumination - the background _of the PMTA is _a

50%

_gray to

render it useable for this evaluation. Measure the corners

and the center of the image on the processed microfilm with

a densitometer

having

an apparature no longer than 2 mm.

(Such as a McBeth TD-101.) The readings should be relatively

close to each _{other, if not,} appropriate adjustments should

be made.

10)

Alignment of

Imaging

System - _place the target in the _position where

material to be microfilmed would normally be located. After

microfilming and _processing, the image of the 11"

x 14" or the 8-"

x 11" format border to the edge of the film is mea

sured with a suitable measuring instrument to check proper po

47

Procedure to be followed in

testing

with PMTA-I & PMTA-II

These steps are not _necessarily the._only pattern that can be used, but

they

are in a logical sequence that would render the most information

out of your system and the shortest amount of time in adjustment.

a) Run pre-exposed sensitometric strips through your processor to check if

it is in control. These strips are exposure controlled and when developed

in your processor can be used to diagnose processor problems. Both East

man Kodak and Bell and Howell produce these strips.

b)

Exposure-adjust the exposure level to yield a

density

of 1.1 + .1 of the

50%

reflectance patch when measured with a transmission densitometer. See

#4.

c) Resolution - _{read center} & _corner resolutions and note if _they meet

your needs. If not, adjustments in the focus might have to be made.

See

#1.

d)

Reduction - _{with an} appropriate measuring

instrument,

measure the reduc

tion and make necessary adjustments if necessary. See

#3.

Note that if

adjustments are _necessary, then the resolution should also be checked

48

e)

Readability

- _{read the}

smallest line possible and judge if acceptable.

See

#2.

f

)

Over all and corner distortion - _with the thick format boarder and the

corner grid _patterns, note if distortion is present and if it is acceptable.

See #5 and

#6.

If a1

more quantitative method _{is needed,} use PMTA-II (see

#7).

g) Evenness of illumination - this is to

check, among other

things,

if

the lights are _{properly aligned,} if _they all have the same

intensity,

or

if there are _any hot spots. To accomplish

this,

read

#9.

h)

Alignment of the image system - this is _{accomplished with} the _{aid of}

the format boarder lines

by

measuring from the lines to the film edge.

See

#10.

i)

Quantitative distortion - measure with a suitable _measuring instrument

distances A and B calculate quantitative distortion. See

#7.

This value

can be used as a measure on how much distortion prevails and can be used

for _setting a quality standard to compare with.

j)

Continous tone - included are

density

patches of

10,

30, 50, 70,

80 per

This is a general outline that can be used in the complete _testing of your

50

List of References

1) "American National Standard Method for

Determing

the

Resolving

Powei

of Photographic Materials,"

ANSI,

PH2.33 -

1969,

July

1969.

2)

ANSI,

PH5. 10-1969. "Method for

Measuring

the Screen Luminance of

Microform Readers With Translucent Screens".

3)

ANSI Standard

Drafting Practices,

ANSI

Y14.2,

"Line Conventions and

Lettering".

4)

Rujkovsky,

G. and James L.

Martin,

"The

Planetary

Camera",

Microfilm

Techniques,

PP

8-10,

Nov.-Dec. 1971.

5)

Dupre,

"Microfilming

Standards and Procedures," Business

Graphics,

PP

6-7, May

1971.

6)

EIA,

"Index of EIA and JEDEC Standards and

Engineering

Publications",

May

1971.

7)

Fromm,

H.

J.,

"Method for

Controlling

the

Quality

of Microimages in

Microreproduction Systems,"

Kodak Research

Laboratories,

Rochester.

8)

Gurley,

"Precision Resolution

Targets,

"

No. 8000 and

8010, Troy,

New

York,

November 1970.

9)

ISO,

"ISO Conventional Typographical Character for

Legibility

Tests

(ISO

Characters),

" ISO Recommendation

R435,

Switzerland,

April 1965.

10)

ISO,

"Microcopies, Legibility

Test," ISO Recommendation

R446,

Switzer

land,

September 1965.

11)

Mees,

C. E. Kenneth and T. H.

James,

"The

Theory

of the Photographic

Process,"

51

12)

Mericsko,

R. J. and K. R.

Collier,

"A Comparison

Study

of Resolving

Power Targets," _R.

I. T. June 1970.

13)

MU-M-38748A,

"Microfiche;

For Engineering/Technical

Data, Reports,

Studies and Related

Data,

Requirements

for,

"

1 December 1970.

14)

MIL-M-9868D,

"Microfilming

of

Engineering

Documents,

35mm,

Require

ments

for",

1 October 1970.

15) T. J.

Morgan, Brit,

J. of Phot. "The Limits of

Legibility

on Micro

film,"

June

6,

1969.

16)

NMA,

"American National Standard Test Chart for

Rotary Microfilming

Machines,"

October 1971.

17)

NMA,

"Glossary

of Terms for

Microphotography

and Reproduction Made

from Microimages,"

Maryland 1964.

18)

NMA,

"Inspection and

Quality

Control Standard - First Generation

(Original)

Silver Halide Microfilm,"

4th

Draft, May

1971.

19)

NMA, MS2-1971,

"Format and

Coding

Standards for Computer Output

Microfilm"

/

20)

Photo Methods for

Industry,

"Tough Target,"

PP

32-33,

June 1971.

21)

SMPTE,

"Specifications for A Super 8 Test Film for Projectors and

Printers,"

RP

32-1969,

New

York, July

1969.

22)

SMPTE,

"Specifications for 35mm Projector Alignment and Screen Image

Quality

Test Film,"

RP40,

September 1970.

23)

Taubes,

Earnest

P.,

"Determining Limites of

Legibility

of Micro film Images,"

Photo Devices

Inc.,

Rochester,

New York.

24)

Underhill,

M.

A.,

"Evaluation of an Alpha-numeric Target as a Means

of

Determining

the Resolution of a Photographic Reconnaissance

System",

ROCHESTER

INSTITUTE OF TECHNOLOGY

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author. If the reader obtains _any assistance

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volume,

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_persons, whose signatures attest their acceptance of the above restrictions.

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In

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